Mercurial > sdl-ios-xcode
diff src/video/SDL_blit.h @ 1047:ffaaf7ecf685
Altivec-optimized blitters!
Vast majority of this work is compliments of Bob Ippolito.
http://www.devolution.com/pipermail/sdl/2005-February/067466.html and many
other posts.
| author | Ryan C. Gordon <icculus@icculus.org> |
|---|---|
| date | Sun, 17 Apr 2005 10:19:22 +0000 |
| parents | b8d311d90021 |
| children | 2651158f59b8 |
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--- a/src/video/SDL_blit.h Sun Apr 17 10:16:30 2005 +0000 +++ b/src/video/SDL_blit.h Sun Apr 17 10:19:22 2005 +0000 @@ -374,6 +374,20 @@ dB = (((sB-dB)*(A))>>8)+dB; \ } while(0) +/* Blend the RGB values of two pixels based on a source alpha value */ +#define ACCURATE_ALPHA_BLEND(sR, sG, sB, sA, dR, dG, dB) \ +do { \ + unsigned tR, tG, tB, tA; \ + tA = 255 - sA; \ + tR = 1 + (sR * sA) + (dR * tA); \ + dR = (tR + (tR >> 8)) >> 8; \ + tG = 1 + (sG * sA) + (dG * tA); \ + dG = (tG + (tG >> 8)) >> 8; \ + tB = 1 + (sB * sA) + (dB * tA); \ + dB = (tB + (tB >> 8)) >> 8; \ +} while(0) + + /* This is a very useful loop for optimizing blitters */ #if defined(_MSC_VER) && (_MSC_VER == 1300) /* There's a bug in the Visual C++ 7 optimizer when compiling this code */